diff --git a/lib/classes/databox/fieldUnknown.class.php b/lib/classes/databox/fieldUnknown.class.php
deleted file mode 100644
index 663c7baf4a..0000000000
--- a/lib/classes/databox/fieldUnknown.class.php
+++ /dev/null
@@ -1,66 +0,0 @@
-<?php
-
-/*
- * This file is part of Phraseanet
- *
- * (c) 2005-2012 Alchemy
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-/**
- *
- * @license     http://opensource.org/licenses/gpl-3.0 GPLv3
- * @link        www.phraseanet.com
- */
-class databox_fieldUnknown extends databox_field
-{
-
-    /**
-     *
-     * @param databox $databox
-     * @param int $id
-     * @return databox_fieldUnknown
-     */
-    public function __construct(databox $databox, $id)
-    {
-        $this->set_databox($databox);
-        $this->sbas_id = $databox->get_sbas_id();
-        $this->id = $id;
-
-        return $this;
-    }
-
-    /**
-     *
-     * @param databox $databox
-     * @param int $id
-     * @return databox_fieldUnknown
-     */
-    public static function get_instance(databox &$databox, $id)
-    {
-        $cache_key = 'field_' . $id;
-        $instance_id = $databox->get_sbas_id() . '_' . $id;
-        if ( ! isset(self::$_instance[$instance_id]) || (self::$_instance[$instance_id] instanceof self) === false) {
-            try {
-                self::$_instance[$instance_id] = $databox->get_data_from_cache($cache_key);
-            } catch (Exception $e) {
-                self::$_instance[$instance_id] = new self($databox, $id);
-                $databox->set_data_to_cache(self::$_instance[$instance_id], $cache_key);
-            }
-        }
-
-        return self::$_instance[$instance_id];
-    }
-
-    /**
-     * Return true because the field is unknown
-     *
-     * @return boolean
-     */
-    public function is_on_error()
-    {
-        return true;
-    }
-}